On a mx6qsabresd revision C board with rev1.2 mx6q, the system gets resetted and it is not able to reach the Linux prompt.

Comparing the watchdog behaviour on a revB versus revC board:

- On a mx6qsabresd revB:

U-Boot > reset resetting ...

U-Boot 2013.01-10524-g432a3aa-dirty (Feb 07 2013 - 13:34:46)

CPU: Freescale i.MX6Q rev1.1 at 792 MHz Reset cause: WDOG ...

- On a mx6qsabresd revC:

U-Boot > reset resetting ...

U-Boot 2013.01-10524-g432a3aa-dirty (Feb 07 2013 - 13:34:46)

CPU: Freescale i.MX6Q rev1.1 at 792 MHz Reset cause: POR

So due to revC POR/watchdog circuitry whenever a watchdog occurs, it causes a POR.

Clearing the PDE - Power Down Enable bit of WMCR registers fixes the problem and is also safe for all mx6 boards.

Signed-off-by: Fabio Estevam fabio.estevam@freescale.com --- Changes since v2: - Using bool can make the code cleaner Changes since v1: - Improve commit log arch/arm/cpu/armv7/mx6/soc.c | 12 ++++++++++++ arch/arm/include/asm/arch-mx6/imx-regs.h | 8 ++++++++ 2 files changed, 20 insertions(+)

diff --git a/arch/arm/cpu/armv7/mx6/soc.c b/arch/arm/cpu/armv7/mx6/soc.c index a8aad5d..6b089f3 100644 --- a/arch/arm/cpu/armv7/mx6/soc.c +++ b/arch/arm/cpu/armv7/mx6/soc.c @@ -30,6 +30,7 @@ #include <asm/arch/clock.h> #include <asm/arch/sys_proto.h> #include <asm/imx-common/boot_mode.h> +#include <stdbool.h>

struct scu_regs { u32 ctrl; @@ -121,12 +122,23 @@ void set_vddsoc(u32 mv) writel(reg, &anatop->reg_core); }

+static void imx_set_wdog_powerdown(bool enable) +{ + struct wdog_regs *wdog1 = (struct wdog_regs *)WDOG1_BASE_ADDR; + struct wdog_regs *wdog2 = (struct wdog_regs *)WDOG2_BASE_ADDR; + + /* Write to the PDE (Power Down Enable) bit */ + writew(enable, &wdog1->wmcr); + writew(enable, &wdog2->wmcr); +} + int arch_cpu_init(void) { init_aips();

set_vddsoc(1200); /* Set VDDSOC to 1.2V */

+ imx_set_wdog_powerdown(false); /* Disable PDE bit of WMCR register */ return 0; }

diff --git a/arch/arm/include/asm/arch-mx6/imx-regs.h b/arch/arm/include/asm/arch-mx6/imx-regs.h index 3eb0081..eaa7439 100644 --- a/arch/arm/include/asm/arch-mx6/imx-regs.h +++ b/arch/arm/include/asm/arch-mx6/imx-regs.h @@ -601,5 +601,13 @@ struct iomuxc_base_regs { u32 daisy[104]; /* 0x7b0..94c */ };

+struct wdog_regs { + u16 wcr; /* Control */ + u16 wsr; /* Service */ + u16 wrsr; /* Reset Status */ + u16 wicr; /* Interrupt Control */ + u16 wmcr; /* Miscellaneous Control */ +}; + #endif /* __ASSEMBLER__*/ #endif /* __ASM_ARCH_MX6_IMX_REGS_H__ */